Recently, with the development of radio communication technology, a mobile communication system capable of high-speed and reliable data transfer has been in use. Particularly, in a mobile packet communication system, which uses the code division multiplexing scheme such as W-CDMA (Wideband-Code Division Multiple Access) and CDMA-2000, a technique in which communication channels are selectively used depending on the characteristics of the signal to be transmitted to a mobile communication terminal is adopted as a method of downward transmission.
For transmission of control signals, the A-DPCH (Associated-Dedicated Physical CHannel) is used which is an individual downward channel (a channel dedicated to each terminal) suitable for high-speed transmission power control. To the contrary, for transmission of data signals, time division multiplexed communication is carried out using the DSCH (Downlink Shared CHannel), which is a common channel that allows radio resources to be used effectively among a plurality of mobile communication terminals. As described above, by appropriately switching the channels to be used depending on the property of the signals, an effective signal transmission is carried out which makes use of the advantages of both channels in a mutually complementary manner.